What c.l.py's opinions about Soft Exception?

castironpi at gmail.com castironpi at gmail.com
Sun Mar 9 21:48:07 CET 2008

D'Aprano suggested callbacks.  How does this work for you?

class SomeNumeric(object):
    def __div__(a, b):
        if b == 0: raise ZeroDivisionError  ## Hard Exception...
        if a == 0: msgboard- ZeroNumerator()
        f = a / b
        i = a // b
        if f == float(i):
            msgboard- IntegerDivision()
            return a // b #? return i?
            msgboard- FloatDivision()
            return a / b #? return f?

If it works, I can write some implementations of msgboard and discuss
its scope.

It sounded at one point like you were augmenting control flow, but you
cleared that up by saying, raise SoftException is not a true raise.

There is a limit to how many behaviors you can fit in a single
statement in any language.  What behaviors is determined by other
choices in the language design.  Those choices have many consequences,
some linguistic, some social, and some personal.  If a dictator always
makes impersonal decisions, which linguistic + social ones should he
make?  If the answer is, "No, we will not strike note J and K because
we elected to strike notes L and M instead", then it's disappointing,
but it might ease that to know what L and M are.

Lastly, that notation I wrote was kind of sly.  I might favor
msgboard( ZeroNumerator() ) or even msgboard.add( ZeroNumerator() ).

How far are you willing to come from the OP's proposal to get it to
work?  If they add something half-way there, but you don't get exactly
what you want, is that fair?

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